1. Technical Field
This invention relates to an electronic device for use with, for example, a digital television receiver or the like. More particularly, the invention relates to an electronic device configured to perform data communication with other devices over a serial data bus.
2. Description of the Related Art
Digital television receivers have recently been proposed which allow for data communication in accordance with the IEEE-1394-1995 high performance serial bus system. The IEEE-1394-1995 standard, promulgated in 1995, provides a universal protocol for data communications over a serial bus. This standard defines a digital interface for data communications, thereby eliminating the need for an application to convert digital data to analog data before it is transmitted across the bus. Likewise, a receiving application will receive digital data from the bus rather than analog data, and will therefore not be required to perform A/D conversion.
The IEEE 1394 standard has been adopted to implement an inexpensive high-speed architecture that supports both asynchronous and isochronous format data transfers. Isochronous data transfers are real-time transfers which take place such that the time intervals between significant instances have the same duration at both the transmitting and receiving applications. Each packet of data transferred isochronously is transferred in its own time period. Multiple channels are provided for isochronous data transfer between applications. A six bit channel number is broadcast with the data to ensure reception by the appropriate device. This allows multiple devices to transmit isochronous data across the bus structure. Asynchronous transfers are traditional data transfer operations which take place as soon as possible and transfer an amount of data from a source to a destination.
Referring to FIG. 13, by way of example, a digital television receiver (hereinafter referred to as “DTV”) 100 serving as an IEEE 1394 node may include subunits such as a tuner 110 and a monitor 120. Monitor 120 includes a video processing section 120A for performing signal processing on inputted video data, such as adjustment of brightness and adjustment of chromaticity; and a display 120B for displaying an image based on the video data that has been signal-processed by video processing section 120A. The display 120B is considered a functional block (termination device) which transforms and “terminates” inputted video data. (Data is considered to be “terminated” when it is used by an end device, such as a display that transforms input data to a displayed image.)
DTV 100 also includes a memory 130 that stores information pertaining to the above-mentioned subunits existing within DTV 100. For example, when monitor 120 is connected to an external electronic device, as indicated in FIG. 13, a plug 120P of monitor 120 interconnected to video processing section 120A is interconnected to a plug 100P of the DTV 100 which is interconnected to the external electronic device.
FIG. 14 shows an example of a related art descriptor having information pertaining to the monitor 120 stored in the above-mentioned memory 130. The stored information enables an external device to readily ascertain, among other things, the logical connection state of video processing section 120A, thereby facilitating data communication with DTV 100.
While the above example illustrates the utility of serial bus connected devices, there is a continuing need to provide ways to facilitate data communication among such devices and improve operability of serial data bus connected systems. The present invention addresses this need.